In recent years, semiconductor integrated circuits, information storage media such as hard disks, micromachines, and the like have been processed in highly fine patterns. In the fields of processing such workpieces, there has widely been used an etching apparatus utilizing a plasma.
As an etching apparatus utilizing a plasma, there has been known an etching apparatus which generates various kinds of beams including a positive ion beam and a radical beam. The positive ion beam or the radical beam is applied to a workpiece, for thereby depositing a film on the workpiece, etching the workpiece, modifying the surface of the workpiece.
One of the most serious problems in the etching process using a high-density plasma is charge build-up damage caused by charges accumulated on the surface of the workpiece. The charge build-up damage is caused due to the difference between the behaviors of electrons and positive ions. Specifically, since electrons have a higher energy and a higher velocity than positive ions, the electrons reach the workpiece faster than the positive ions, so that a negative potential is developed on the surface of the workpiece. The negative potential thus developed accelerates the positive ions and decelerates the electrons. At this time, those electrons which are decelerated to become nondirectional cannot be introduced into fine patterns on the surface of the workpiece, but only the positive ions reach the bottom of the fine patterns. Therefore, a positive charge build-up is developed on the workpiece to cause etching profile irregularities or charge build-up damage.